The present invention is generally directed to an improved access port, such as access ports suitable for providing in-plant processing of air conditioning and refrigeration systems and for connecting standard field service equipment to same, for units that are typically charged with fluids, e.g., refrigerants. The term “fluid” as used in this disclosure is not limited to refrigerants and may include other liquids, gases, or liquid-gas mixtures. Among other applications, an access port in accordance with the present invention may find use in residential and commercial air conditioning systems or the like.